I'm using FEBE wiht FF 53.0.2 on my private computer at home and I try to use it on my office-pc.I'm syncronize my Account with FF-Sync and all of my addons are complete instead FEBE.When I install FEB everything means OK.On the next day FEBE is disapeard in the list of my addons.There are no error mesages and I dont know what to do.

To be honest, I haven't used Firefox Sync or know much about how it works. But I do have some questions for you.

When you go to Firefox Sync Options (type about:preferences#sync in the address bar), does it indicate that you are logged in? If you are logged in you should have your Firefox account name and a button to "Disconnect..." in the "Firefox Account" box.

In the "Sync across all devices" section, is the "Add-ons" box checked? If it is, try un-checking it to see if it resolves the problem.

Is FEBE the only extension that gets deleted?

When you install FEBE, does Fx complain about it not being compatible?

You mentioned that FEBE disappears the next day. Do you restart Fx every day? Is FEBE gone immediately after a restart or does it disappear by itself without a restart?

Q:When you go to Firefox Sync Options (type about:preferences#sync in the address bar), does it indicate that you are logged in? If you are logged in you should have your Firefox account name and a button to "Disconnect..." in the "Firefox Account" box.A: Yes, I'm connected.

Q: In the "Sync across all devices" section, is the "Add-ons" box checked? If it is, try un-checking it to see if it resolves the problem. A: Yes, all checkboxes are checked and No, uncheckung Add-ons do not solve the problem.

Q: Is FEBE the only extension that gets deleted?A: Yey, only FEBE is missing.

Q: When you install FEBE, does Fx complain about it not being compatible?A: No, there are no messages.

Q: You mentioned that FEBE disappears the next day. Do you restart Fx every day? Is FEBE gone immediately after a restart or does it disappear by itself without a restart?A: FF ist restart every day. My work-computer is a virtual-fat-client and the VM behind is always running. I'm logging off from Windows 7 when I leaving work. All programs will be stopped. The next day I'm loggin on in Windows 7 and FF is started by click on the icon.

BTW: When I close FF while working and start it again FEBE ist still present.

Perhaps FEBE is being removed by your anti-virus program. Does it run overnight? Is there a way to see if FEBE is being quarantined or removed? I don't know what anti-virus program you use, but there is usually a log of its activity created somewhere that can be checked.

Is the anti-virus on the VM (assuming your are running one) different from the host? Does the host anti-virus check the VM file contents?

No, there is no anti-virus-program on my computer-system. Anti-virus is running out of the box on the NeApp.If FEBE becomes to be an victim of anti-virus I get an mail with this info.I think it's a FF-sync-problem - do you know of a sync-log?